When does x<=a and x>=0 have a solution

Garth Isaak, Lehigh University

abstract:

We will try to have some fun exploring the mathematical connections 
between the following:

When does a system of linear inequalities have a solution?
When does a system of pipelines have a feasible flow?
When does an order relation represent `comes before' for intervals in 
time?
When does a list of numbers represent the win records for a round-robin 
tournament?